# HG changeset patch
# User Paul Boddie <paul@boddie.org.uk>
# Date 1373752409 -7200
# Node ID eba69418c451d9a0442a79da84f746a322e99323
# Parent  66479525a9fc3c0144974f64eed6a15add31d06c
Fixed interval level setting on selectors and retention of specific recurrence details.
Added detection of inappropriate interval qualification (where a broader
selector qualifies a narrower selector).

diff -r 66479525a9fc -r eba69418c451 RecurrenceSupport.py
--- a/RecurrenceSupport.py	Sat Jul 13 01:33:22 2013 +0200
+++ b/RecurrenceSupport.py	Sat Jul 13 23:53:29 2013 +0200
@@ -17,6 +17,11 @@
   repeating-recurrence = every [ <qualifier> ] <interval>
                          [ from <specific-recurrence> ]
                          [ until <specific-recurrence> ]
+
+Constraints:
+
+  repeating-recurrence: if <qualifier> is not "single":
+                        from and/or until must be specified
 """
 
 from DateSupport import weekday_labels, month_labels
@@ -31,6 +36,12 @@
     }
 
 def isQualifier(qualifier, qualifiers):
+
+    """
+    Return whether the 'qualifier' is one of the given 'qualifiers', returning
+    the level of the qualifier.
+    """
+
     if qualifiers.has_key(qualifier):
         return qualifiers[qualifier]
     if qualifier.endswith("th") or qualifier.endswith("nd") or qualifier.endswith("st"):
@@ -94,6 +105,9 @@
 class ParseError(Exception):
     pass
 
+class VerifyError(Exception):
+    pass
+
 class ParseIterator:
     def __init__(self, iterator):
         self.iterator = iterator
@@ -159,7 +173,7 @@
             self.recurrence_type, self.qualifier, self.interval,
             self.from_datetime and " from {%s}" % self.from_datetime or "",
             self.until_datetime and " until {%s}" % self.until_datetime or "",
-            self.qualified_by and ", in %s" % self.qualified_by or "")
+            self.qualified_by and ", selecting %s" % self.qualified_by or "")
 
     def __repr__(self):
         return "Selector(%s, %s, %s%s%s%s>" % (
@@ -194,6 +208,15 @@
     return current
 
 def parseRecurrence(words, current):
+
+    """
+    Using the incoming 'words' and given the 'current' selector, parse a
+    recurrence that can be either a repeating recurrence (starting with "every")
+    or a specific recurrence (starting with "the").
+
+    The active selector is returned as a result of parsing the recurrence.
+    """
+
     words.next()
     if words.have("every"):
         parseRepeatingRecurrence(words, current)
@@ -205,30 +228,52 @@
         raise ParseError, words.tokens
 
 def parseSpecificRecurrence(words, current):
+
+    """
+    Using the incoming 'words' and given the 'current' selector, parse and
+    return a specific recurrence.
+    """
+
+    # Handle the qualifier and interval.
+
     qualifier = words.next()
     qualifier_level = isSpecificQualifier(qualifier)
     if not qualifier_level:
         raise ParseError, words.tokens
     interval = words.next()
-    interval_level = intervals.has_key(interval)
+    interval_level = intervals.get(interval)
     if not interval_level:
         raise ParseError, words.tokens
 
     current.add_details("the", qualifier, qualifier_level, interval, interval_level)
 
+    # Detect the intervals becoming smaller.
+
+    if current.qualified_by and current.interval_level < current.qualified_by.interval_level:
+        raise ParseError, words.tokens
+
+    # Define selectors that are being qualified by the above qualifier and
+    # interval, returning the least specific selector.
+
     words.want()
     if words.have("in"):
         current = Selector(current)
         words.need("the")
-        parseSpecificRecurrence(words, current)
+        current = parseSpecificRecurrence(words, current)
 
     return current
 
 def parseRepeatingRecurrence(words, current):
+
+    """
+    Using the incoming 'words' and given the 'current' selector, parse and
+    return a repeating recurrence.
+    """
+
     qualifier = words.next()
     if intervals.has_key(qualifier):
         interval = qualifier
-        interval_level = intervals.has_key(interval)
+        interval_level = intervals.get(interval)
         qualifier = "single"
         qualifier_level = isRepeatingQualifier(qualifier)
     else:
@@ -236,17 +281,36 @@
         if not qualifier_level:
             raise ParseError, words.tokens
         interval = words.next()
-        interval_level = intervals.has_key(interval)
+        interval_level = intervals.get(interval)
         if not interval_level:
             raise ParseError, words.tokens
 
     current.add_details("every", qualifier, qualifier_level, interval, interval_level)
 
+    # Detect the intervals becoming smaller.
+
+    if current.qualified_by and current.interval_level < current.qualified_by.interval_level:
+        raise ParseError, words.tokens
+
 def parseOptionalLimits(words, current):
+
+    """
+    Using the incoming 'words' and given the 'current' selector, parse any
+    optional limits, where these only apply to repeating occurrences.
+    """
+
     if current.recurrence_type == "every":
         parseLimits(words, current)
 
 def parseLimits(words, current):
+
+    """
+    Using the incoming 'words', parse any limits applying to the 'current'
+    selector.
+    """
+
+    from_datetime = until_datetime = None
+
     if words.have("from"):
         words.need("the")
         from_datetime = Selector()
@@ -259,4 +323,10 @@
         until_datetime = parseSpecificRecurrence(words, until_datetime)
         current.set_until(until_datetime)
 
+    # Where the selector refers to a interval repeating at a frequency greater
+    # than one, some limit must be specified to "anchor" the occurrences.
+
+    elif not from_datetime and current.qualifier_level != 1:
+        raise ParseError, words.tokens
+
 # vim: tabstop=4 expandtab shiftwidth=4
diff -r 66479525a9fc -r eba69418c451 tests/test_recurrence.py
--- a/tests/test_recurrence.py	Sat Jul 13 01:33:22 2013 +0200
+++ b/tests/test_recurrence.py	Sat Jul 13 23:53:29 2013 +0200
@@ -1,12 +1,91 @@
 #!/usr/bin/env python
 
-from RecurrenceSupport import getRecurrence
+from RecurrenceSupport import getRecurrence, ParseError
+
+# Good recurrences.
+
+s = "every single day of the second month"
+print s
+print "->", getRecurrence(s)
+s = "every single day of the second month of every year"
+print s
+print "->", getRecurrence(s)
+s = "every other day from the first day of every other month from the third month of every year"
+print s
+print "->", getRecurrence(s)
+s = "the second day of every other month from the first month"
+print s
+print "->", getRecurrence(s)
+s = "the second hour in the second day in the second month of every year"
+print s
+print "->", getRecurrence(s)
+s = "every day from the second day until the 10th day of every other month until the fifth month"
+print s
+print "->", getRecurrence(s)
+s = "every day from the 10th day in the second month until the 10th day in the 10th month of every third month from the first month"
+print s
+print "->", getRecurrence(s)
+s = "every day of every third month from the 10th day in the second month until the 10th day in the 10th month"
+print s
+print "->", getRecurrence(s)
+
+# Bad recurrences.
+
+print
+
+# No start or end points.
+
+s = "every other day of every other month"
+print s
+try:
+    print "->", getRecurrence(s)
+except ParseError, exc:
+    print exc
 
-print getRecurrence("every other day of every other month")
-print getRecurrence("the second day of every other month")
-print getRecurrence("every other day of every other month from the third month of every year")
-print getRecurrence("every day from the second day until the 10th day of every other month")
-print getRecurrence("every day from the 10th day in the second month until the 10th day in the 10th month of every third month")
-print getRecurrence("every day of every third month from the 10th day in the second month until the 10th day in the 10th month")
+s = "every other day of every other month from the third month of every year"
+print s
+try:
+    print "->", getRecurrence(s)
+except ParseError, exc:
+    print exc
+
+s = "the second day of every other month"
+print s
+try:
+    print "->", getRecurrence(s)
+except ParseError, exc:
+    print exc
+
+s = "every day from the second day until the 10th day of every other month"
+print s
+try:
+    print "->", getRecurrence(s)
+except ParseError, exc:
+    print exc
+
+s = "every day from the 10th day in the second month until the 10th day in the 10th month of every third month"
+print s
+try:
+    print "->", getRecurrence(s)
+except ParseError, exc:
+    print exc
+
+# Syntax error: need to use "of" instead of "in".
+
+s = "every single day in the second month"
+print s
+try:
+    print "->", getRecurrence(s)
+except ParseError, exc:
+    print exc
+
+# Out of order: days do not contain months.
+
+s = "every other month from the first month of every other day from the first day"
+print s
+try:
+    print "->", getRecurrence(s)
+except ParseError, exc:
+    print exc
 
 # vim: tabstop=4 expandtab shiftwidth=4